With the rapid development of science and technology, the processing technology of the electronics industry has also made great progress. In order to make it more convenient for customers to carry, the volume of products in the electronics industry is getting smaller and smaller. Highly integrated, high-performance miniature electronic products have been loved by people. The SMT technology in the electronics industry is widely used. It has now replaced traditional electronic assembly technology in many fields and is considered a revolutionary change in electronic assembly technology.

1 SMT technology research

1.1 Screen printing technology

The so-called screen printing refers to the printing of solder paste on the PCB pads. The printing methods include contact type stencil printing and screen printing without direct contact.

The first step of screen printing is to stir the solder paste. During the stirring process, attention must be paid to the viscosity and uniformity of the solder paste. Viscosity has a direct effect on the quality of printing. Generally, we will determine the printing viscosity according to the printing standard.

The storage environment of solder paste requires a temperature of 0-5°C. In this environment, the components in the solder paste will naturally separate. For this reason, the solder paste should be taken out and placed at room temperature for 20 minutes to allow it to heat up naturally. Then we use the glass rod to stir, the stirring time is 10-20min. The use of solder paste also has requirements for the environment. The ideal environment requires a temperature of 20-25°C and a humidity of 40%-60%.

Printing solder paste on PCB pads is the front-end work of SMT technology production, and makes sufficient preparations for the soldering of components. Practical results show that the silk screen solder paste can not only improve the soldering quality, but also make the amount of solder paste on the PCB pads fuller.

1.2 Component mounting technology

Mounting components is mainly for the assembly of components that can be installed on the PCB. During printing and production, the mounting components are different in form and position, so program coding must be done when mounting them on the PCB position accurately.

After the mounting is completed, we need to adjust the position, and take effective measures to do laser recognition and camera recognition.

1.3 Reflow soldering technology

Before putting the printed board into the reflow soldering, we need to check all aspects such as the mounting position of the component. Reflow soldering usually includes four steps: preheating, heat preservation, reflow and cooling.

The purpose of preheating is to ensure that its temperature is balanced and stable. The temperature of the holding room should be kept at 180℃, and the temperature difference should not be too large. The degree of moisture retention must be within 40%-60% of the condition. When heating, we generally set the heater temperature to 245℃. After being sent out of the reflow oven, the temperature of the PCB board will gradually cool down, allowing the solder joints to achieve the best results.

2 Development prospects and trends of SMT technology

At present, the competition among various industries in various countries in the world is becoming more and more fierce, and the cost pressure is relatively high. The SMT industry technology has demonstrated its system integration in functions such as automatic intelligence, assembly, and logistics.

With the advancement of science and technology, the degree of automation of SMT technology is getting higher and higher, labor costs are greatly reduced, and personal output has increased a lot. The main theme of the future development of SMT technology will develop towards high performance, high flexibility, ease of use and environmental protection.

(1) With the intensive development of the electronics industry, competition has become increasingly fierce. The improvement of environmental protection requirements and the development of the miniaturization trend of electronic products have created higher requirements for SMT technology. High precision, high speed and high environmental performance are the mainstream trends in the development of SMT technology, and the placement head will also realize automatic conversion.

(2) In the past few years, the SMT market has undergone many changes, and customers need to manufacture a wide variety of electronic products with high mixing and small and medium-sized batches.

In addition, more and more people like wearable products, so we need to incorporate more functions into a smaller unit volume. At the same time, to achieve assembly in an extremely small area, the technology will become more and more complex. How to achieve high stability, high precision and relatively reliable printing and placement at high speed is a bottleneck in the development of SMT technology.

(3) As the volume of electronic products shrinks and functions increase, the density of components will gradually increase. Now semiconductor manufacturers pay much attention to the application of high-speed placement machines, and SMT production lines will also apply some semiconductor integration area technologies. Therefore, the integration of semiconductor packaging technology and SMT technology is the trend of industry development.